DIY Solar Install

[nsgoldberg]

Hi All,

First post but have been lurking on the forum for a couple of months now. I'm planning on installing a roof mount, grid-tied, solar array on my home and doing it myself. I'm about to pull the trigger but I would like those of you who are more knowledgeable than I to look over my plan and let me know if you see any issues with it or areas I can improve.

Usage:
Location: Southern CA, Inland, essentially desert (zip code 92570)
Current Usage: 8,000 kWh over previous 12 months (hardly any A/C usage, would like to use more though)
Planned size: 7.5kW
PVWatts Estimate @ 7.5 kW: 12,600 kWh/yr
Planning on buying an EV later this year:
20,000 mi/yr @ 5 km/kWh = 6,400 kWh/yr
Usage with EV = 14,400 kWh/yr

Permitting:
I'm a licensed Mechanical Engineer, but my county (Riverside) requires an electrical engineer and a structural or civil engineer to stamp the plans for a permit. I considered making the plans myself and paying for a EE/CE to review and stamp them, however, it seems there isn't a huge cost difference between that and having a company generate the plans and stamp them for me. Yoursolarplans.com will generate all the plans, the worksheets required by the county, and have it all stamped for $675. I then have to pay the permit fee of $458 to the county. The PoCo and county AHJ are fine with DIY install and connection, as long as the permit is done and the county signs off on the inspection.

System Specs:
I'm looking at a 7.5kW system on WholesaleSolar.com ($11,000):

https://www.wholesalesolar.com/1891572/wholesale-solar/complete-systems/7.5-kw-grid-tied-solar-system-with-solaredge-and-20-mission-solar-375-watt-panels

Panels: 20 Mission Solar 375W Silver Mono PERC
Inverter: SolarEdge SE10000H HD-Wave 10kW
(Inverter is oversized to allow the addition of panels in the future)
Optimizers: 20 SolarEdge P400 Optimizers
Also comes with IronRidge XR100 Racking, clips, hardware, labeling, grounding bars kit, disconnect, etc.
I would only need to purchase the wire, conduit, and flashing to complete the system (Home Depot, est. $600).

I will have two strings of 10 panels connected to the inverter. Inverter will be Ethernet connected. All panels will be on roof surfaces at the same azimuth and tilt, facing South. No shade will fall on the panels.

Summary:
Therefore, the total system will cost around $12,700, or $1.70/watt ($1.19/watt after 30% federal rebate).

Please let me know if there's anything I missed or can improve on, or perhaps a better route (i.e. cheaper) with the permitting. Thanks for the wealth of information this site has given me so that I could get to this point!

[Markyrocks69]

The only thing I can say is that you could probably save some money by sourcing the equipment from different vendors. That's not going to be as convenient as a all inclusive kit but I paid around the same price for a system twice that size.

Also be aware that if you're planning on doing the install yourself that those panels are big. So going to be a challenge getting them onto a roof without a second person or a machine.

[JSchnee21]

Welcome nsgoldberg!

Sounds like you've got this planned out pretty well! Some general comments:

1) You PoCo may give you a hard time with the PV array size and projected production being great than 100% of current historical usage. Some tolerate up to 110-120%. Other's don't seem to check the estimated production (PVWatts) very carefully so sometimes you can get away with estimating low.

2) I don't have any experience with the Mission Solar panels so I cannot comment one way or another, but they see to have gotten a decent rating on EnergySage if that's worth anything -- maybe, maybe not. But in general, panels are a commodity, and most mid tier panels are fine. The Temperature Coefficient of Pmax is -0.375%/

[JSchnee21]

oh darn, it clipped the rest of my post

[ButchDeal]

with an inverter over 7.6kW you will have to have a lineside tap or derate you MSP most likely.

Since you are planning to add an EV charger you could save a bit of money and have a much simpler interconnect (assuming a 200a MSP) without a lineside tape or derate bu using the SE7600H, further you could get the SE7600H with a built in EV charger.

You say that all the PV modules will be on the same azimuth and tilt but will the expansion be on the same azimuth and tilt? if not then the SE7600H may not clip even with over paneling.
even so you can go a bit over 7.6kW with modest clipping and/or add an SE3800h for expansion latter.

https://www.solaredge.com/us/products/ev-charger#/

[J.P.M.]

Welcome to the neighborhood.

I worked in the Inland Empire for several years when I first moved to CA, now retired in 92026. Now have a mostly unobstructed view to the north from the San Gabriels all the way past the west end of Big Bear to San Gorgonio. Smile for the camera.

How much clearance are you designing for roof to bottom of panel frame ? Respectful suggestion: The more the better.

Also, if not done so already, check roof setback requirements per CA/Riverside co. fire codes.

Assuming SCE is your POCO, on SCE and size limitations etc.: You've probably seen the SCE application checklist by NEM program type, but if not, it might be worth your time. It looks like you will need "electrical system sizing documentation" for a system w/est. output > prior 12 months and so jump through that hoop if a system's whose proposed estimated annual production based on their NEM interconnection handbook is > prior 12 month's usage. But it look to be STC wattage restricted beyond the required forms to be filed being different for < vs > 10 kW STC size.

Lastly, get your roof inspected/serviced if/as you think necessary. Cheap insurance you will not regret. PV will last a long time. Chasing roof leaks is bad enough. Chasing them under an array is a nearly impossible task. Give the roof the best chance of lasting at least as long as the array.

Regards,

Add: almost missed it: You may need another jump through another hoop if you do need a line side tap as Butch writes.

[foo1bar]

Hi All,
I'm looking at a 7.5kW system on WholesaleSolar.com ($11,000):
Panels: 20 Mission Solar 375W Silver Mono PERC

I'd look at other vendors. I think you can do better than $11k.
I'd look at renvu, soligent.

I did a DIY install with 60-cell panels, and those were awkward to handle - 72-cell panels are going to be singificantly worse IMO.
Also - I would look at lower efficient (but better $/W) panels.
For example, you could get 72-cell 365W for $180.20/panel ($.49/W)
26 of those would give you more power for cheaper I think.
There's some cost per-panel for optimizer, rails, etc. etc. So it isn't all about the per-panel cost (just mostly)
I'd also look at 60-cell 275W @ $.45/W (more optimizers, but easier to handle I think)

[nsgoldberg]

Wow, a lot of great tips and suggestions here, thank you all! Did some research on what was said here before responding.

The only thing I can say is that you could probably save some money by sourcing the equipment from different vendors. That's not going to be as convenient as a all inclusive kit but I paid around the same price for a system twice that size.

Also be aware that if you're planning on doing the install yourself that those panels are big. So going to be a challenge getting them onto a roof without a second person or a machine.

I'm going to look at this, do you have a recommended source? I plan on using my neighbor's tractor to lift them on the roof. (One side is relatively low).

Welcome nsgoldberg!

Sounds like you've got this planned out pretty well! Some general comments:

1) You PoCo may give you a hard time with the PV array size and projected production being great than 100% of current historical usage. Some tolerate up to 110-120%. Other's don't seem to check the estimated production (PVWatts) very carefully so sometimes you can get away with estimating low.

2) I don't have any experience with the Mission Solar panels so I cannot comment one way or another, but they see to have gotten a decent rating on EnergySage if that's worth anything -- maybe, maybe not. But in general, panels are a commodity, and most mid tier panels are fine. The Temperature Coefficient of Pmax is -0.375%/

You're right, I wasn't aware of this, thanks!

with an inverter over 7.6kW you will have to have a lineside tap or derate you MSP most likely.

Since you are planning to add an EV charger you could save a bit of money and have a much simpler interconnect (assuming a 200a MSP) without a lineside tape or derate bu using the SE7600H, further you could get the SE7600H with a built in EV charger.

You say that all the PV modules will be on the same azimuth and tilt but will the expansion be on the same azimuth and tilt? if not then the SE7600H may not clip even with over paneling.
even so you can go a bit over 7.6kW with modest clipping and/or add an SE3800h for expansion latter.

https://www.solaredge.com/us/products/ev-charger#/

I hadn't considered the need for a lineside tap or derating my MSP. I realize now this is a big issue, especially once I add the charger for an EV.

If I have a 200A breaker and bus, isn't that 40A or 9.6kW?

The additional panels would be the same azimuth and tilt.

I have an older breaker panel that uses a strange main breaker. I don't ever flip it, because half the time I do, it won't reset. You can't find them new, but there's a company in LA that rebuilds them for $300. I've had to do that twice now to get power back on in the house. I'm considering upgrading the entire panel to a modern one. That might be a good time to install a line side tap. How common is this, and what costs would be incurred in putting that in? I'm guessing I would need to hire an electrician to do that, and another ($$$) permit from the county.

Perhaps I should just stick with the 7.6kW inverter. But, if I expand later, that's going to require a derate, correct?

On another note, the sum of the breakers in my 200A panel is 470A. Would that be an issue during inspection?

Welcome to the neighborhood.

I worked in the Inland Empire for several years when I first moved to CA, now retired in 92026. Now have a mostly unobstructed view to the north from the San Gabriels all the way past the west end of Big Bear to San Gorgonio. Smile for the camera.

How much clearance are you designing for roof to bottom of panel frame ? Respectful suggestion: The more the better.

Also, if not done so already, check roof setback requirements per CA/Riverside co. fire codes.

Assuming SCE is your POCO, on SCE and size limitations etc.: You've probably seen the SCE application checklist by NEM program type, but if not, it might be worth your time. It looks like you will need "electrical system sizing documentation" for a system w/est. output > prior 12 months and so jump through that hoop if a system's whose proposed estimated annual production based on their NEM interconnection handbook is > prior 12 month's usage. But it look to be STC wattage restricted beyond the required forms to be filed being different for < vs > 10 kW STC size.

Lastly, get your roof inspected/serviced if/as you think necessary. Cheap insurance you will not regret. PV will last a long time. Chasing roof leaks is bad enough. Chasing them under an array is a nearly impossible task. Give the roof the best chance of lasting at least as long as the array.

Regards,

Add: almost missed it: You may need another jump through another hoop if you do need a line side tap as Butch writes.

Very nice! I like that area. I remember reading 3' roof setback, I have it currently planned for ~2'. I've been paying attention to installations all around the county, and most are right to the edge of the roof. So it doesn't seem to be something the county is strict about.

You're right, I will need documentation for a larger installation. Hopefully they will accept the rationale of planning on buying an EV.

Our roof is in great shape, but I think I'll pull some tiles to confirm prior to installation, and do a good look underneath in the attic. Thanks for the tip!

I'd look at other vendors. I think you can do better than $11k.
I'd look at renvu, soligent.

I did a DIY install with 60-cell panels, and those were awkward to handle - 72-cell panels are going to be singificantly worse IMO.
Also - I would look at lower efficient (but better $/W) panels.
For example, you could get 72-cell 365W for $180.20/panel ($.49/W)
26 of those would give you more power for cheaper I think.
There's some cost per-panel for optimizer, rails, etc. etc. So it isn't all about the per-panel cost (just mostly)
I'd also look at 60-cell 275W @ $.45/W (more optimizers, but easier to handle I think)

Good point, I think I'll take a look at the smaller panels. Easier to install, and easier to fit in spaces on the roof.

[nsgoldberg]

Found this regarding roof space:

"Identify any existing mechanical equipment on the roof plan and provide a minimum working clearance of 36" around the entire unit as well as a minimum 24" wide clear accessway from the roof scuttle or roof access point. (NEC 110.26 and CMC 904.10)"

So I believe it's OK to go to the edge of the roof, provided you have 24" clear where you will climb onto the roof.

[ButchDeal]

I hadn't considered the need for a lineside tap or derating my MSP. I realize now this is a big issue, especially once I add the charger for an EV.

As I suggested you can get the SE7600H with built in inverter so only one 40A breaker.

If I have a 200A breaker and bus, isn't that 40A or 9.6kW?

No a 7.6kW inverter requires a 40A breaker

The additional panels would be the same azimuth and tilt.

Then if there is no shadows you will have some clipping unless you add another inverter like the SE3800H later.

I have an older breaker panel that uses a strange main breaker. I don't ever flip it, because half the time I do, it won't reset. You can't find them new, but there's a company in LA that rebuilds them for $300. I've had to do that twice now to get power back on in the house. I'm considering upgrading the entire panel to a modern one. That might be a good time to install a line side tap. How common is this, and what costs would be incurred in putting that in? I'm guessing I would need to hire an electrician to do that, and another ($$$) permit from the county.

Same permit can be used but you can get new 200A MSP with higher amp bus which would allow a larger inverter without a lineside tap. This would be the way to go.

Perhaps I should just stick with the 7.6kW inverter. But, if I expand later, that's going to require a derate, correct?

or you could replace the MSP at that time.

On another note, the sum of the breakers in my 200A panel is 470A. Would that be an issue during inspection?

That is common as you generally do not run EVERYTHING at once. and most of the items on those breakers are not maxed out.

[ButchDeal]

Found this regarding roof space:

"Identify any existing mechanical equipment on the roof plan and provide a minimum working clearance of 36" around the entire unit as well as a minimum 24" wide clear accessway from the roof scuttle or roof access point. (NEC 110.26 and CMC 904.10)"

So I believe it's OK to go to the edge of the roof, provided you have 24" clear where you will climb onto the roof.

do you have a flat roof? you need firecode setback on your roof which are generally 3 feet from ridge and rake (simplified a bit)

https://www.renvu.com/Learn/New-California-Setback-Rules-July-1st-2018

[nsgoldberg]

Great info, thanks for the quick response! I see now, there's an 80% deration, so it's not based on 40A, but actually 32A.

Apparently my PoCo (SCE), has meter adapters already set up for line side taps just for solar. They're called "Generation Meter Adapters" or GMA. There are pictures of it on page 20 here:

https://www.sce.com/sites/default/files/custom-files/pdf/5527_SCE_IneractiveFAQ_AA.pdf

This may be the best route. Edison will install the GMA (it's really just a spacer) for close to $500 and connect it to your disconnect. Kind of a rip off for $500, but still cheaper and easier than MSP replacement, even if I do the work myself.

[nsgoldberg]

do you have a flat roof? you need firecode setback on your roof which are generally 3 feet from ridge and rake (simplified a bit)

https://www.renvu.com/Learn/New-Cali...-July-1st-2018

This is great info, thanks! According to this, then yes, I will need 3' from ridge and side. I don't have a flat roof.

This will make it more difficult to place the panels I've chosen. I may need to go with the 60 cell for a better fit. I made a drawing in AutoCAD for it, so I'll have to play with that a bit.

[ButchDeal]

Great info, thanks for the quick response! I see now, there's an 80% deration, so it's not based on 40A, but actually 32A.

no it is based on a 40A breaker in the MSP.
The 40A breaker is based on the derate and requirements of the inverters. THUS, a 7.6kW inverter spits out 32A and requires a 40A breaker AND that is the max you can fit on an older 200A MSP with a 200A buss.

[ButchDeal]

Also comes with IronRidge XR100 Racking, clips, hardware, labeling, grounding bars kit, disconnect, etc.
I would only need to purchase the wire, conduit, and flashing to complete the system (Home Depot, est. $600).

I would HIGHLY suggest that you use the IronRidge flashing system and not get some flashing from Homedepot.

https://www.ironridge.com/pitched-roof-mounting/introducing-flashfoot2/